It’s unlikely from laomian because that is a dish, relatively newer, not the noodle itself which is lamian. A majority of Japanese words originating from China is closer to the Cantonese sound (laaimin) rather than Mandarin. One example – en:embassy = jp:taishikan = zh-yue:daaisigun = zh:dashiguan. Another – en:six = jp:roku = zh-yue:lok = zh:liu (but en:five = jp:go = zh-yue:ng = zh:wu is closer to zh-hak:go).